One of the most controversial issues in medicine is whether providers should be evaluated in terms of their adherence to sim-ple metrics. Such metrics have become increasingly popular as away to improve the quality of health care. For example, under theAffordable Care Act, Accountable Care Organizations are judged onthe basis of criteria including: The fraction of patients who receiveinfluenza immunization, tobacco screening, and other forms ofscreening, as well as whether patients with coronary artery diseaseare taking appropriate medications, and other such metrics.